1. Field of the Invention
The present invention relates to a debugging apparatus referred to as a viewer for analyzing and displaying measured data in a semiconductor test and a method of displaying test results.
2. Description of the Related Art
The resolution of imaging devices such as CCD chips is greatly increasing at present. The growing resolution of imaging devices requires imaging device tests to handle and process a very large amount of information.
Generally, when developing and testing image capturing devices or imaging devices such as CCDs, CMOS imagers, etc., it has been customary to capture an image of a test pattern with a device under test, output the captured image from the device, and inspect image data of the captured image processed for color filtering, smoothing, etc. to determine whether the device under the test is acceptable or not. To determine the acceptability of the tested device, the numerical values of the processed image data are inspected for all the pixels. In the inspection, it has been the general practice to employ an apparatus dedicated for testing imaging devices and automatically select those imaging devices whose values fall in a certain range according to a test program.
Recently, however, more and more imaging devices are tested using general-purpose semiconductor testing apparatus (so-called IC testers). When such a general-purpose IC tester is used to test an imaging device, no test pattern is employed, but the imaging device is placed on a test head connected to the IC tester, and irradiated with light to conduct the test. The operator operates a personal computer connected to the IC tester to analyze and display test results.
One conventional image inspection process is disclosed in Japanese laid-open patent publication No. 7-230546, for example. According to the disclosed image inspection process, an inspected image is displayed as a histogram and analyzed.
During a development stage for imaging devices, a test program often incorporates steps of displaying or printing processed results as binary, octal, or hexadecimal numerical values for the operator to confirm the processed results. Occasionally, the displayed and printed data may cover the values of all pixels of an imaging device being tested. In recent years, imaging devices with several million pixels have been developed and manufactured as such digital cameras are finding widespread use among consumers.
According to a conventional process of displaying test information, the characteristic value of each pixel is usually represented by an analog gradation, and those characteristic values of plural pixels are simultaneously displayed to generate an image of captured data on a display unit. Specific numerical values for pixels can be displayed by moving a cursor or the like, and can be retrieved when necessary. When such pixel information is displayed as areas with varying brightness and darkness (luminance information) on the display unit, the operator can recognize the general tendency of the pixel information. However, the operator finds it difficult to determine and compare specific values, such as specific numerical values for certain pixels and differences between specific numerical values for adjacent pixels, e.g., upper, lower, left, and right pixels, from only the displayed pixel information.
Even though the test program incorporates the steps of displaying or printing all numerical data of pixels of an imaging device for confirmation, it is tedious and time-consuming for the operator to confirm a certain area of pixels because the numerical data are too many if the number of the pixels in the imaging device is very large. If a range to be displayed is specified in the displaying step, then when such a range is changed, the displaying step incorporated in the test program has to be changed. For displaying numerical values, they should not only be dumped and displayed successively in the order of addresses, but also be dumped while relative positions of the addresses are being calculated taking the arrangement of the pixels in the imaging device into consideration, so that, for example, the numerical values of horizontally adjacent pixels can be compared with each other and also the numerical values of vertically and obliquely adjacent pixels can be compared with each other. If the number of vertically and horizontally arrayed pixels is very large, then special care must be taken to dump and display the numerical values of the pixels. A large expenditure of labor and time may be required to incorporate, in each test program, the displaying step taking into account the proper relationship between an area that needs to be displayed and the addresses of original data.
For observing the tendency among codes representing the characteristics of each dot in an imaging device under test, the codes may be displayed as characters or symbols directly over a map which is displayed on a display screen as representing the imaging device. However, since the codes displayed as characters or symbols take up relatively large areas on the display screen, the range that can be displayed by the codes at once is more limited than the range that can be displayed using dots, and hence all the data cannot be displayed together on the display screen.
Also a display unit is known for displaying a dot image of visual luminance information converted from original data or processed data.